When researchers announced they'd discovered a giant cave creature with teeth and claws in Australia, you'd be forgiven for picturing something terrifying. Something with fangs. Something enormous.

Researchers found dozens of tiny, see-through crustaceans in an Australian cave, including a new “giant” species measuring nearly 6mm (not pictured). JURE MAKOVEC AFP via Getty Images Beneath a remote ...

More than 1,500 massive underground tunnels have been found in southern Brazil. Some stretch longer than six football fields. The structures were not carved by humans, according to researchers.